During the process of manufacturing semiconductor devices, numerous contact structures are required to be formed. For the dynamic random access memory (DRAM), the contact structures include bit-line contact vias, substrate contact vias, gate contact vias, and etc. Through these contact vias, the conductive lines contacted to the source/drain, the substrate, and the gate can be formed. For example, the methods of manufacturing the above structures have been disclosed in U.S. Pat. No. 6,780,739 and Taiwan Patent Application 92128778.
In the current silicon process, a titanium nitride layer, which is generally formed by chemical vapor deposition process, is often used as a diffusion barrier layer. For example, a titanium layer and a titanium nitride layer are deposited prior to filling the bit-line contact hole with metal. However, the impurities may be implanted into the titanium nitride layer during the deposition, affects the conductivity of the titanium nitride layer and even results in open circuit failures.
Therefore, it is necessary to provide a method of manufacturing a contact structure to solve the open circuit issue.